TrailingHeadersTest.cs: CS4007 ReadOnlySpan<byte> cannot be preserved across await boundary

[matouskozak]

Build Information

Build: 1347491
Leg Name: windows-x64 Release AllSubsets_Mono

TrailingHeadersTest.cs(220,36) uses a ReadOnlySpan<byte> across an await boundary, which is disallowed by the compiler. This is a code defect in the System.Net.Http.WinHttpHandler functional tests.

Build log

Error Message

{
    "ErrorMessage": "error CS4007: (NETCORE_ENGINEERING_TELEMETRY=Build) Instance of type 'System.ReadOnlySpan<byte>' cannot be preserved across 'await' or 'yield' boundary.",
    "BuildRetry": false,
    "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1347491
Error message validated: [error CS4007: (NETCORE_ENGINEERING_TELEMETRY=Build) Instance of type 'System.ReadOnlySpan<byte>' cannot be preserved across 'await' or 'yield' boundary.]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 3/23/2026 10:23:25 AM UTC

Report

Build	Definition	Step Name	Console log	Pull Request
1347815	dotnet/runtime	Build product	Log	#125948
1347491	dotnet/runtime	Build product	Log

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
2	2	2

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